1. Field of the Invention
The present invention relates, in general, to bumpers mounted to the front and rear ends of vehicles and, more particularly, to a bumper apparatus with a multistage energy absorbing structure.
2. Description of the Related Art
A bumper apparatus of a vehicle functions to absorb shock energy applied to the front or rear end of a vehicle, thus protecting both the car body of the vehicle and passengers traveling in the vehicle.
In the related art, to meet bumper laws requiring 5-mile-per-hour bumper standard, a conventional bumper apparatus comprises a shock absorber, made of EPP (expanded polypropylene) with a foaming ratio of 15, a back beam and a bumper cover. However, in Europe, a bumper apparatus having improved shock absorbing performance has been required to protect pedestrians from bumper impacts according to tougher bumper laws increased to a 2.5-mile-per-hour bumper standard, so that the bumper apparatuses in Europe use EPP with a foaming ratio of 45.
Particularly, in recent years, a bumper apparatus, which can continuously maintain the reliable shock absorbing effect in a collision and can easily restore its original shape after the collision, is required.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.